Incinerator

ABSTRACT

An incinerator having a closed combustion chamber includes an exhaust gas separator for separating and directing the lighter inert exhaust gases into a stack and the heavier exhaust gases, including smoke and other solid materials, into a recirculation system for recirculation through the combustion chamber. Air required to support combustion is admitted into the recirculation system and mixed with and heated by the exhaust gases being recirculated before entering the combustion chamber, thereby permitting the temperature in the combustion chamber to increase to a level sufficient to assure complete burning of the combustible materials in the exhaust gases recirculated into the combustion chamber and to normally sustain combustion without auxiliary burners except during the beginning and end portions of a burning cycle. The exhaust gas velocity is reduced in the gas separator to facilitate separation and recirculation of the heavier exhaust gases and solids.

United States Patent 191 Gibeault I INCINERATOR [75] Inventor: Robert E.Gibeault, South Glens Falls,

[73] Assignee: Kleenaire Recycling Systems, Inc.,

Ft. Edward, N.Y.

22 Filed: Apr..4, 1973 21 Appl.No.:347,740,

[52] U.S. Cl. 110/8 C, 110/8 A, llO/49 R [51] Int. Cl F23g [58] Field ofSearch 110/8 R, 8 C, 8 A, 18 R, 1 10/18 C, 49 R [56] References CitedUNITED STATES PATENTS 1,679,909 8/1928 Michael et a1. 110/49 3,485,19112/1969 Christman 110/119 X 3,538,865 1 1/1970 Lausmann l 110/1193,749,031 7/1973 Burden,Jr. llO/49 X R24,844 7/1960 Bouchard 110/8Primary Examiner-Kenneth W. Sprague Attorney, Agent, or F irm-Browne,Beveridge, DeGrandi & Kline June 11, 1974 ABSTRACT An incinerator havinga closed combustion chamber includes an exhaust gas separator forseparating and directing the lighter inert exhaust gases into a stackand the heavier exhaust gases, including smoke and other solidmaterials, into a recirculation system for recirculation through thecombustion chamber. Air required to support combustion is admitted intothe recirculation system and mixed with and heated by the exhaust gasesbeing recirculated before entering the combustion chamber, therebypermitting the temperature in the combustion chamber to increase to alevel sufficient to assure complete burning of the combustible materialsin the exhaust gases recirculated into the combustion chamber and tonormally sustain combustion without auxiliary burners except during thebeginning and end portions of a burning cycle. The exhaust gas velocityis reduced in the gas separator to facilitate gases and solids.

10 Claims, 4 Drawing Figures 1 INCINERATOR BACKGROUND OF THE INVENTIONl. Field of the Invention This invention relates to fuel burners such asfurnaces, boilers, and incinerators, and more particularly to such afuel burner which includes means for separating and recirculatingthe-heavier gases and unburned solids from the burner exhaust to therebyincrease the efficiency of the unit and to reduce the smoke and otherpollutents emitted therefrom. Since the invention is especially welladapted for use in incinerators of the type commonly employed to burntrash. garbage, and other waste products, it will be particularlydescribed herein as incorporated in such an incinerator, it beingunderstood that the invention is not so limited and that the termincinerator as used herein'should be interpreted broadly enough toinclude furnaces and the like as well as waste material incinerators.

2. Description of the Prior Art 7 Various attempts have been made torecycle the combustion gases released from fuel such as trash andgarbage burned in an incinerator in order to produce a clean, smokelessstack exhaust which is not repugnant to the smell and which meetsincreasingly stringent anti-pollution standards. Prior apparatus hasusually attempted to reduce the particulate matter and unburnedhydrocarbons and other noxious gases, commonly known as saturated gases,in the stack exhaust by placing a duct on the side of the stack or flueand employing a suction fan to withdraw a portion of the stack gases andunburned matter and reintroduce them into the combustion chamber. Thesedevices have generally been unsuccessful in substantially reducing thesaturated gases due to the fact that traveling particles, whether largeor of molecular size, tend to travel in a straight line due to momentum.Thus, an attempt to withdraw the objectional gases from the total flowof gas in the stack has resulted in recirculating only a small portionof the heavier saturating gases which inherently are difficult to divertfrom their flow path due to their greater inertia. Due to this inabilityto separate and withdraw substantial portions of the heavier saturatedgases, prior apparatus has been burdened with additional equipment suchas secondary burn chambers where the exhaust gases are subjected, forexample to natural gas flames, scrubbers, and electrostaticprecipitators, which additional equipment has necessarily added to theexpense and complexity of the device, and frequently has even added toone or another form of pollution. Further, these added features arestill often not capable of removing an adequate amount of the saturatedgases to meet modern emission standards.

Another disadvantage of prior incineration apparatus, particularly whenused to destroy or burn waste material, has been the inability tosustain combustion without the use of auxiliary fuel furnaces. Thisproblem has been aggravated by the quenching or cooling effect of thecombustion air which is generally admitted into the combustion chamberat ambient temperature and in volumes greatly in excess of that requiredfor the combustion of the material being burned. Further, when stackgases have been recirculated, they have generally been withdrawn at apoint substantially removed from the combustion chamber and much oftheir'heat is lost before they are reintroduced intothe combustionchamber.

SUMMARY OF THE INVENTION The present invention overcomes the above andother disadvantages of the prior art by providing an incinerator with anexhaust gas recycling apparatus such that virtually all of the heaviergases and unburned solids are separated from the lighter stack gases and.returned to the combustion chamber to be completely incinerated.Accordingly, it is a primary object of this invention to provide animproved incinerator which is highly efficient in operation and whichemits a minimum of smoke and other pollutents.

Another object of this invention is to provide an incinerator whereinthe'heavier gases and unburned solids are separated from the exhaustgases and recycled through the combustion chamber.

It is another object of this invention to provide such an improvedincinerator which eliminates the need for secondary exhaust gascombustion or scrubbing apparatus.

A further object of this invention is to provide such an incineratorwhich normally requires no auxiliary fuel burnersfor burning mostcombustible wastes once a minimum combustion chamber temperature issurpassed.

The foregoing and other objects are achieved in an improved. incineratoraccording to the present invention which includes a combustion chamberfor receiving a charge of material to be burned, air inlet means toadmit air to support combustion and an exhaust outlet in communicationwith an exhaust stack for withdrawing the exhaust gases. A gasseparation chamber connected to the exhaust outlet has two substantiallyopposed outlet ports, one of which is connected directly to the exhauststack and the other is connected to a recycling duct. A constriction islocated in the combustion chamber exhaust outlet adjacent the inlet tothe separation chamber to produce a relatively high velocity in theexhaust gases as they enter the separation chamber. The increasedcross-sectional area, or volume, of the separation chamber results in anabrupt and substantial reduction in the velocity of the exhaust gases asthey pass from the exhaust outlet into the separation chamber. Thereduction in velocity in the separation chamber facilitates separationof the heavy gases and unburned solids (saturated gases) from theremaining lighter exhaust gases, with the saturated gases being drawninto the recycling duct where they are mixed with a predetermined amountof ambient air and reintroduced into the combustion chamber for completecombustion. The lighter gases (inert gases) are exhausted to theatmosphere via the exhaust stack.

BRIEF DESCRIPTION OF THE DRAWINGS of the struc- 3 FIG. 4 is a sectionalview taken along line4-4 of no. 1. I

DESCRIPTION OF THE PREFERRED EMBODIMENT wall to form a substantiallyair-tight closure during operation of the incinerator.

An elongated generally rectangular air manifold 30 is mounted on therear wall 18 and an auxiliary air blower 32 of conventional constructionis provided to supply air to the manifold. Three air supply tubes 34,36, 38 are mounted in fluid communication with manifold 30 and extendthrough the rear wall 18 adjacent the bottom thereof for supplyingcombustion air within the combustion chamber 12 along the bottom wall24. Suitable cover plates 40, each having air openings at spacedintervals therealong, are provided above the air supply tubes along thebottom wall 24 to distribute air along the full length of the combustionchamber adjacent each side and along the center thereof.

A conventional fuel burner assembly 42, including a fuel nozzle 44, ismounted on the rear wall 18, with the nozzle 44 being positioned todirect a flame downwardly and toward the front wall of the combustionchamber during operation of the burner. The fuel burner 42 incorporatesa pyromcter or other temperature sensor for sensing the temperaturewithin the combustion chamber and for stopping the fuel burner when thecombustion chamber temperature reaches a predetermined level and foragain igniting the burner when the temperature subsequently falls belowthe predetermined minimum as combustion of the incinerator charge nearscompletion.

An exhaust outlet 46 is provided in the top wall 22 adjacent the rearcentral portion thereof to provide an escape for the combustion gasesfrom the combustion chamber. Mounted on the wall 22'above the opening46, and in fluid communication therewith, is a short verticallyextending conduit or pipe section 48 which, in turn, is connecteddirectly into the side of a short horizontaliy extending conduit or pipesection 50. The pipe sections 48, 50 are assembled in the form of a pipetee, with the tee section forming a separation. chamber for the exhaustgases as described more fully hereinbelow.

One leg of the pipe 50 extends toward the front of the incinerator abovewall 22 and is connected to a downwardly inclined pipe section 52connected to a return opening 54 in wall 22 to provide a recirculationpath or duct leading back into the recirculation chamber 12 for aportion of the gases exiting through outlet 46. The opposite end of thepipe 50 is directly connected, through an elbow 56, to an exhaust stack58 having a barometric damper 60 mounted therein for admitting air andthereby controlling the pressure within the stack.

A conventional draft inducing fan or blower 62 is mounted on the conduit50 in position to induce a draft through the recirculation duct 52 backinto the combustion chamber l2. The fan 62 is driven, through belt 64 bya conventional electric motor 66 mounted on the top of wall 22. Anopening 68 is provided in the blower housing 70 to admit combustion airto be drawn into the fan to be mixed with and'heated by the exhaustgases being recirculated beforethe mixture is reintroduced into thecombustion chamber. The volume of combustion air introduced into thecombustion chamber may be controlled by a movable cover plate 72slidably mounted on the housing 70 in position to cover the opening 68.As indicated by the arrow 74 in FIG. 4, the cover plate 72 may be movedup or down, as desired, to cover any portion of the opening 68 tothereby provide the desired volume of combustion air admitted into therecirculation duct 52.

An adjustable baffle 76 is slidably'mounted within the pipe section 50at the intersection of conduit 48 to provide an adjustable obstructionto the flow of gases out the exhaust stack 58. As indicated by the arrow78,

the position of the baffle 76 may be adjusted to provide the desiredbalance of flow between the recirculation duct and the exhaust stack,depending upon burning conditions.

In order to provide a more even distribution of the gas beingrecirculated into the combustion chamber 12, and to provide for moveeven distribution of the combustion air admitted through blower 68,'aplurality of branch conduits are provided leading from the recirculationduct 52 to convey a portion of the recirculated gas-air mixture into thecombustion chamber at different points. Thus, a pair of conduits 80, 82leading from the duct 52 enter the chamber through the side walls 14,16, respectively, and a second pair of conduits 84, 86 lead from theduct 52 to the opposed ends of the manifold 30, with branch outletsindicated generally at 88, 90 leading through the side walls 14, 16.Thus, the recirculated gases passing through the ducts 84, 86 will bedivided, with a portion reentering the combustion chamber through thebranch outlets 88, 90 and the remainder passing from manifold 30 throughthe air supply tubes 34, 36 and 38. Thus, while most of the recirculatedgases and combustion air mixture enters the combustion chamber throughopening 54, a sufficient quantity of this mixture is admitted at otherpoints to assure uniform complete combustion.

In operation of an incinerator according to the present invention, thecombustion chamber is completely charged through the door 26 with a loadof material to be burned, and the door 26 is replaced and sealed.Burning is commenced by operation of the auxiliary burner to ignite thecharge of material and to assist in the combustion until the temperaturewithin the combustion chamber reaches the desired temperature. Also, atthe beginning of the burning cycle, the blower 32 is operated to supplycombustion air into the bottom of the combustion chamber, therebyassuring an adequate supply of combustion air to initiate and sustainfull combustion of the fuel during operation of the auxiliary burner.

The draft control or recirculation fan is continuously driven to createa draft in the recirculation duct 52 so that all combustion gases andany excess combustion air exits the combustion chamber 12 through theoutlet 46. The cross-sectional area of the outlet 46 is substantiallyless than the area of the pipe 48, and is particularly less than thecombined areas of the opposed ends of the horizontally extending pipe 50so that the velocity of the exhaust gas is substantially reduced as itpasses from the restricted outlet 46 to the separation chamber definedby the pipe sections 48 and 50. Further, as indicated in FIG. 3, theconstricted exhaust outlet 46 may have its walls inclined to produce aVenturi effect, thereby accelerating the gases as they pass through theoutlet. The abrupt velocity change as the gases pass through theconstricted outlet 46 produces a tendency for the lighter or inert gasesto separate from the heavier gases and unburned solids, apparently dueto a snow fence effect, which separation facilitates'the removal andrecirculation of the saturated gases while permitting the inert gases toescape up the stack 58. The gas separation in the separation chamber isin two stages, the first taking place immediately following the exhaustoutlet 46 and the second stage produced by the further velocityreduction and direction change taking place as the gases enter the tube50 and separate into two flow paths. The effect of the baffle 56 also isto impart a velocity component to the heavier gases and solids in thedirection of the recirculation duct rather than toward the exhauststack. This velocity component combined with the draft induced by fan 62results in the heavier gases being recirculated while the lighter inertgases are permitted to escape up the stack.

As the temperature within the combustion chamber 12 reaches a level tosustain combustion without the aid of the auxiliary fuel, burner 42 isautomatically shut-off and at the same time blower 32 is stopped. Sincethe combustion chamber is essentially sealed, the only combustion airentering the chamber is-admitted through the opening 68 in the housing70 of the draft inducing blower 62. This combustion air is thoroughlymixed with the very hot exhaust gases and reintroduced into thecombustion chamber at a relatively high temperature so that there islittle quenching effect by the introduction of the combustion air. Thispreheating of the combustion air, coupled with the careful control ofthe volume of combustion air admitted during this phase of theoperation, permits operation of the incinerator throughout the majorportion of the burning cycle without the use of auxiliary fuel. Theamount of air required for complete, smoke-free combustion can readilybe determined by experiment or by reference to available publications.The optimum amount of combustion air will depend upon the type of fuelbeing burned, the temperature within the combustion chamber and othervariables which may readily be determined to maintain the desiredcombustion air flow into the incinerator while at the same time assuringagainst excessive air flow which reduces the burning temperature and mayincrease the amount of smoke and other solids such as fly ash in theexhaust.

An important feature of the invention also resides in a carefullycontrolled balance between the pressures within the exhaust stack andthe pressure within the recirculation chamber. Obviously, excessivedraft in the stack would overcome the effect of the draft inducing fan62 while too little draft would result in poor combustion and eventualfailure. The barometric damper 60 can readily be adjusted to maintainthe desired control by admitting greater or lesser amounts of ambientair into the stack to control the draft. Thus, during initial start up,the damper 60 will normally be closed, but will gradually open astemperature of the exhaust gases builds up to increase the draft.

While I have disclosed and described a preferred embodiment of myinvention, I wish it understood that I do not intend to be restrictedsolely thereto, but that I do intend to include all embodiments thereofwhich would be apparent to one skilled in the art in which come withinthe spirit and scope of my invention.

What is claimed is:

1. In an incinerator of the type including an enclosed combustionchamber for receiving a charge of material to be burned and havingairinlet means for admitting air to support combustion and an exhaustoutlet, and an exhaust stack connected in fluid communication with saidexhaust outlet for withdrawing exhaust gases from said combustionchamber, the improvement comprising a gas separation chamber having aninlet connected to said exhaust outlet and first and second outletports. said first outlet port being connected to said exhaust stack,recycling duct means including a conduit having one end connected tosaid second exhaust port and its other end connected to a recycling portin said combustion chamber to permit recirculation of saturated exhaustgases from said separation chamber into said combustion chamber, meansproducing a substantial reduction in velocity of the exhaust gasesbetween said exhaust outlet and said separation chamber to therebyfacilitate separation of the saturated gases from the combustion chamberfor recycling thereto, said recycling duct means includes a plurality ofconduits each communicating with said combustion chamber for deliveringthe recycled gases into said combustion chamber at different points,blower means connected in said recycling duct for withdrawing only aportion of the exhaust gases from said separation chamber andrecirculating the withdrawn portionthrough said duct into saidcombustion chamber, vent means connected to said blower for admitting acontrolled amount of ambient air into said recycling duct means wherebyair from said vent and the recirculated exhaust gases are mixed in saidrecycling duct before entering said combustion chamber, and barometricdamper means for admitting air into said stack, said damper beingoperative to control the pressure in said stack and thereby the pressureat said first outlet port of said separation chamber to enable saidblower to withdraw and recirculate said saturated gases.

2. The incinerator as defined in claim 1 wherein said means producingsaid reduction in velocity of the exhaust gases comprises means defininga constriction in said exhaust outlet to produce a relatively highvelocity past said constriction, said separation chamber having asubstantially larger cross-sectional area than said constriction wherebythe gas velocity issubstantially reduced as it passes from saidconstriction into said separation chamber.

3. The incinerator as defined in claim 1 wherein said first and saidsecond outlet ports are positioned in substantially opposed relation toone another and on opposed sides of said exhaust outlet and lie inplanes generally parallel to the direction of flow of the exhaust gasesthrough said exhaust outlet whereby the exhaust gases entering saidseparation chamber from said exhaust outlet must alter directionssubstantially before exiting through either of said outlet ports.

4. The incinerator as defined in claim 3 further comprising baffle meansin said separation chamber for deflecting gases passing through saidexhaust outlet toward said second outlet port, said baffle means being7. adjustable to vary the extent of deflection of said gases passingthrough said exhaust outlet.

5. The incinerator as defined in claim 3 further comprising auxiliaryburner means operable to initiate combustion within said combustionchamber and to maintain the temperature in said combustion chamber abovea predetermined minimum.

6. An incinerator comprising. in combination. an enclosed combustionchamber for receiving a charge of combustible material to be burnedtherein, means sealing said chamber to prevent the uncontrolled flow ofair into the chamber, an exhaust outlet in said chamber, a gasseparation chamber having an inlet connected to said exhaust outlet anda pair of outlet ports, said outlet ports being spaced from one anotherand offset with respect to said inlet whereby exhaust gases enteringsaid separation chamber from said combustion chamber through saidexhaust outlet are compelled to materially change directions beforepassing through either of said outlet ports, an exhaust stack connectedto one of said outlet ports for withdrawing exhaust gases from saidseparation chamber, a recirculation duct having one end connected to theother of said outlet ports and its other end connected to arecirculation port in said combustion chamber, blower means connected tosaid recirculation duct and operable to withdraw a portion of theexhaust gases from said separation chamber and to recirculate thewithdrawn portion through said duct and into said combustion chamber,vent means for admitting air into said combustion chamber at acontrolled rate, said vent means including means admitting air into saidrecirculation duct at a point to be mixed with and preheated bysaidportion of the exhaust gases being recirculated and before enteringsaid combustion chamber, and barometric damper means for controlling thepressure in said stack at said first outlet port.

7. The incinerator as defined in claim 6 further comprising gas velocitycontrol means producing a substantial reduction in velocity of theexhaust gases within said separation chamber to thereby facilitateseparation and recirculation of the heavier gases and particulatematerial from the exhaust gases entering said separation chamber fromsaid combustion chamber.

8. The incinerator as defined in claim 7 wherein said velocity controlmeans comprises means defining a constriction in said exhaust outlet,said constriction being operable to produce a high exhaust gas velocitythrough said constriction, said separation chamber having across-sectional area immediately adjacent said constriction which issubstantially greater than the cross-sectional area of saidconstriction.

9. The incinerator as defined in claim 6 wherein said constrictiondefines means defining an elongated generally rectangular orificepositioned within the path of the exhaust gases at said exhaust outlet.Y

10. The incinerator as defined in claim 9 furthe comprising auxiliaryburner means operable to initiate combustion within said combustionchamber and to maintain the temperature in said combustion chamber abovea predetermined minimum.

1. In an incinerator of the type including an enclosed combustionchamber for receiving a charge of material to be burned and having airinlet means for admitting air to support combustion and an exhaustoutlet, and an exhaust stack connected in fluid communication with saidexhaust outlet for withdrawing exhaust gases from said combustionchamber, the improvement comprising a gas separation chamber having aninlet connected to said exhaust outlet and first and second outletports, said first outlet port being connected to said exhaust stack,recycling duct means including a conduit having one end connected tosaid second exhaust port and its other end connected to a recycling portin said combustion chamber to permit recirculation of saturated exhaustgases from said separation chamber into said combustion chamber, meansproducing a substantial reduction in velocity of the exhaust gasesbetween said exhaust outlet and said separation chamber to therebyfacilitate separation of the saturated gases from the combustion chamberfor recycling thereto, said recycling duct means includes a plurality ofconduits each communicating with said combustion chamber for deliveringthe recycled gases into said combustion chamber at different points,blower means connected in said recycling duct for withdrawing only aportion of the exhaust gases from said separation chamber andrecirculating the withdrawn portion through said duct into saidcombustion chamber, vent means connected to said blower for admitting acontrolled amount of ambient air into said recycling duct means wherebyair from said vent and the recirculated exhaust gases are mixed in saidrecycling duct before entering said combustion chamber, and barometricdamper means for admitting air into said stack, said damper beingoperative to control the pressure in said stack and thereby the pressureat said first outlet port of said separation chamber to enable saidblower to withdraw and recirculate said saturated gases.
 2. Theincinerator as defined in claim 1 wherein said means producing saidreduction in velocity of the exhaust gases comprises means defining aconstriction in said exhaust outlet to produce a relatively highvelocity past said constriction, said separation chamber having asubstantially larger cross-sectional area than said constriction wherebythe gas velocity is substantially reduced as it passes from saidconstriction into said separation chamber.
 3. The incinerator as definedin claim 1 wherein said first and said second outlet ports arepositioned in substantially opposed relation to one another and onopposed sides of said exhaust outlet and lie in planes generallyparallel to the direction of flow of the exhaust gases through saidexhaust outlet whereby the exhaust gases entering said separationchamber from said exhaust outlet must alter directions substantiallybefore exiting through either of said outlet ports.
 4. The incineratoras defined in claim 3 further comprising baffle means in said separationchamber for deflecting gases passing through said exhaust outlet towardsaid second outlet port, said baffle means being adjustable to vary theextent of deflection of said gases passing through said exhaust outlet.5. The incinerator as defined in claim 3 further comprising auxiliaryburner means operable to initiate combustion within said combustionchamber and to maintain the temperature in said combustion chamber abovea predetermined minimum.
 6. An incinerator comprising, in combination,an enclosed combustion chamber for receiving a charge of combustiblematerial to be burned therein, means sealing said chamber to prevent theuncontrolled flow of air into the chamber, an exhaust outlet in saidchamber, a gas separation chamber having an inlet connected to saidexhaust outlet and a pair of outlet ports, said outlet ports beingspaced from one another and offset with respect to said inlet wherebyexhaust gases entering said separation chamber from said combustionchamber through said exhaust outlet are compelled to materially changedirections before passing through either of said outlet ports, anexhaust stack connected to one of said outlet ports for withdrawingexhaust gases from said separation chamber, a recirculation duct havingone end connected to the other of said outlet ports and its other endconnected to a recirculation port in said combustion chamber, blowermeans connected to said recirculation duct and operable to withdraw aportion of the exhaust gases from said separation chamber and torecirculate the withdrawn portion through said duct and into saidcombustion chamber, vent means for admitting air into said combustionchamber at a controlled rate, said vent means including means admittingair into said recirculation duct at a point to be mixed with andpreheated by said portion of the exhaust gases being recirculated andbefore entering said combustion chamber, and barometric damper means forcontrolling the pressure in said stack at said first outlet port.
 7. Theincinerator as defined in claim 6 further comprising gas velocitycontrol means producing a substantial reduction in velocity of theexhaust gases within said separation chamber to thereby facilitateseparation and recirculation of the heavier gases and particulatematerial from the exhaust gases entering said separation chamber froMsaid combustion chamber.
 8. The incinerator as defined in claim 7wherein said velocity control means comprises means defining aconstriction in said exhaust outlet, said constriction being operable toproduce a high exhaust gas velocity through said constriction, saidseparation chamber having a cross-sectional area immediately adjacentsaid constriction which is substantially greater than thecross-sectional area of said constriction.
 9. The incinerator as definedin claim 6 wherein said constriction defines means defining an elongatedgenerally rectangular orifice positioned within the path of the exhaustgases at said exhaust outlet.
 10. The incinerator as defined in claim 9further comprising auxiliary burner means operable to initiatecombustion within said combustion chamber and to maintain thetemperature in said combustion chamber above a predetermined minimum.